I have a Bobcat ZTR with a 25hp Kawi. It has about 2000 well maintained hours but has been used as backup, secondary for the last couple years. It was working well when we parked it in the corner this fall. Went to move it today and no right side drive. The pump whines like it is working. So far I checked all the lines are tight. Releif valve is closed tight. Checked the linkages and they are tight and not binding. Jacked unit up and wheel turns fine by hand no clicking or catching it feels just like the left side. When you engage it in the air the wheel operates forward and back. I ran it this way thinking it had air in it but after 30 minutes I could still stop the wheel from turning with my hands and on the ground it will not turn. In the air the pump has almost no whine until it has resistance from the wheel then it whines. The left side is working fine. I was going to change the fluid again before spring. It was done last at 1500 hours. This machine is really in good shape so if I have to put a pump in it I am fine with that just want to be sure. Before I spend the $400 on a pump etc what else should I check? Or is it the pump?